However, now when I use the "M2E Z Offset Adjustment (v0.5.0)" the extruder (now dual) just keeps trying to push far left (almost like it's trying to go off rail) which ends up making this loud grinding sound for about 5 seconds (which is because it keeps trying move left on the rail with no more room) and then it goes back to working normally...

Has anyone experienced this or know what I'm referring to? I feel pretty confident about the install overall.

Thank you for helping me figure out what on Earth was going on! I finally broke down & took the plunge to upgrade from my trusty V3b, and thought everything was going well until I tried to print and the initial homing resulted in KXKXKXKXKCHXKXKXKCHXKXKCHCHCXXKCHCHK!